Chapter 4, Problem 4.7P

(a)

Interpretation Introduction

Interpretation:

The average thickness of the liquid film flowing down over the pieces of packing is to be determined.

Concept Introduction:

The thickness mentioned here is the total thickness which a liquid layer makes for a given type of flow. Averaging it will give the average thickness of the layer.

The average thickness is thus given as,

  $\text{δ}\text{=}{\left(\frac{\text{3μΓ}}{{\text{ρ}}^{\text{2}}\text{gcos}\varphi }\right)}^{\frac{\text{1}}{\text{3}}}$ ....... (1)

The notations used here are,

  $\text{μ}$ = Viscosity of the fluid

  g = Acceleration due to gravity

  $\text{ρ}$ = Density of the fluid

  $\Gamma$ = Liquid loading

  $\varphi$ = Angle of inclination

The liquid loading is given as,

  $\text{Γ}\text{=}\frac{\text{<mover accent="true"><mo>m</mo><mo>˙</mo></mover>}}{\text{b}}$ ....... (2)

  $\text{<mover accent="true"><mo>m</mo><mo>˙</mo></mover>}$ = Mass flow rate of the fluid

  b = Breadth of layer in direction perpendicular to the plane

(b)

Interpretation Introduction

Interpretation:

The fraction of the column volume taken up by the liquids is to be determined.

Concept Introduction:

The fraction of the volume in the column taken up by the liquid is called the liquid holdup and it is given by the product of the film thickness and the area per cubic volume.

Liquid Holdup = $\text{δ}\text{×}{\text{A}}_{\text{1}}$ ....... (1)

  $\text{δ}$ = Liquid film thickness

  ${\text{A}}_1$ = Surface area of rings

(c)

Interpretation Introduction

Interpretation:

The average thickness of the liquid film for half wetted total packing surface is to be determined.

Concept Introduction:

The fraction of the volume in the column taken up by the liquid is called the liquid holdup and it is given by the product of the film thickness and the area per cubic volume.

Liquid Holdup = $\text{δ}\text{×}{\text{A}}_{\text{1}}$ ....... (1)

  $\text{δ}$ = Liquid film thickness

  ${\text{A}}_1$ = Surface area of rings